package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        // 缓存穿透
//        Shop shop = cacheClient.queryWithPassThrough(RedisConstants.CACHE_SHOP_KEY, id, Shop.class, this::getById, RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 互斥锁解决缓存击穿
        Shop shop = cacheClient.
                queryWithMutex(RedisConstants.CACHE_SHOP_KEY, id, Shop.class, this::getById, RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 逻辑过期解决缓存穿透
//        Shop shop = cacheClient.
//                queryWithLogicalExpire(RedisConstants.CACHE_SHOP_KEY, id, Shop.class, this::getById, RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if (shop == null) {
            return Result.fail("店铺不存在");
        }

        return Result.ok(shop);
    }

    /**
     * 使用互斥锁解决缓存击穿问题
     * @param id
     * @return
     */
    /*public Shop queryWithMutex(Long id) {
        // 1.从Redis查询缓存
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        // 2.缓存存在，直接返回
        if (StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        // 判断命中的是否是空值，缓存穿透问题，使用空值缓存解决
        if (Objects.equals(shopJson, "")) {
            return null;
        }

        // 实现缓存重建
        // 获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            if (!tryLock(lockKey)) {
               // 获取锁失败，休眠，重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            // 获取锁成功，开启独立线程，实现缓存重建
            // 缓存不存在，查询数据库
            shop = getById(id);
            if(shop == null){
                // 4.数据库不存在，返回错误，将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            // 6.数据库存在，写入缓存
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放锁
            unLock(lockKey);
        }
        return shop;
    }*/

//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 用逻辑过期解决缓存击穿
     * @param id
     * @return
     */
    /*public Shop queryWithLogicalExpire(Long id) {
        // 1.从Redis查询缓存
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        // 2.缓存存在，直接返回
        if (StrUtil.isBlank(shopJson)) {
            return null;
        }
        // 命中需要判断过期时间，反序列化
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop =  JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        // 判断是否过期
        // 未过期，返回店铺信息
        if(expireTime.isAfter(LocalDateTime.now())) {
            return shop;
        }
        // 过期，缓存重建
        // 获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 成功，开启新线程，实现缓存重建
        if (isLock) {
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });
        }

        // 返回过期的店铺信息
        // 6.返回
        return shop;
    }*/

    /**
     * 使用缓存空值解决缓存穿透问题
     * @param id
     * @return
     */
    /*public Shop queryWithPassThrough(Long id) {
        // 1.从Redis查询缓存
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        // 2.缓存存在，直接返回
        if (StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }

        // 判断命中的是否是空值，缓存穿透问题，使用空值缓存解决
        if (Objects.equals(shopJson, "")) {
            return null;
        }

        // 3.缓存不存在，查询数据库
        Shop shop = getById(id);
        if(shop == null){
            // 4.数据库不存在，返回错误，将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);

            return null;
        }

        // 5.数据库存在，写入缓存
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 6.返回
        return shop;
    }*/


    /*private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", RedisConstants.LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }*/

    /**
     * 缓存预热
     * @param id
     */
    public void saveShop2Redis(Long id, Long expireTime) throws InterruptedException {
        Shop shop = getById(id);
        // 模拟延迟
        Thread.sleep(200);

        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireTime));

        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));

    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2.删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY + id);

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.MAX_PAGE_SIZE;
        int end = current * SystemConstants.MAX_PAGE_SIZE;
        // 3.查询redis，按照距离排序，分页查询，结果：shopId、distance
        String key = RedisConstants.SHOP_GEO_KEY + typeId;
        // geosearch key bylonlat x y byradius 5000 withdist
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
        );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取从from到end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询shop
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + StrUtil.join(",", ids) + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
